Mr. Moto (Silva) is back, but not in his usual surroundings of Hawaii. This time the famous Interpol agent is working in London. The evil Dargo, an ex-Nazi, thinks he has killed Silva when he tosses him into the river. But Mr. Moto returns and gets involved in foiling a sabotage attempt involving Middle East oil production. In disguise, Mr. Moto learns that Dargo is pressuring the Middle East people to give in along with Beta Oil Company of Britain. An executive's secretary is kidnaped for company secrets, and Mr. Moto must rescue her. He kills Dargo, arrests his henchmen, and the world's oil supply is safe once more.